Biel/Bienne weather in September

In September, Biel/Bienne sees average daytime highs of 18°C and overnight lows near 10°C, with 114 mm of rain across 13.9 wet days and about 12.4 hours of daylight. It is the 4th-warmest and 5th-wettest month of the year here.

Highs ease over the month, from about 20°C in the first days to 16°C by the end. The sky is clear or mostly clear about 25% of the time in September, and the air most often feels dry.

Daylight stretches from about 13 h 12 min at the start of September to 11 h 30 min by month's end. Set against the rest of the year, September is Biel/Bienne's 3rd-clearest and 11th-windiest month. For the whole year in context, see Biel/Bienne's year-round climate.

Daytime high
18°
4th warmest
Overnight low
10°
9th coldest
Rainfall
114 mm
13.9 wet days
Daylight
12 h 18 min
6:15 AM – 6:35 PM
Cloud cover
63%
3rd clearest
Wind
7 km/h
11th windiest
Solar energy
3.57 kWh/m²
Travel score
5.3
out of 10

Biel/Bienne is Settlement within the Swiss municipality of the same name.

Air quality
Good
PM2.5 9.1 µg/m³ · 2020

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 20°C in the first days to 16°C by the end.

A typical September day in Biel/Bienne reaches about 18°C in the afternoon and slips back to 10°C overnight — a 9°C spread between the day's warmth and the night's chill. On most days the high lands between 13°C and 24°C. Set against its neighbours, September runs about 4°C cooler than August and about 5°C warmer than October.

10°20°30°151015202530
Avg high (°C)Avg low (°C)
12112
22011
32011
42011
52011
62011
72011
81911
91911
101910
111910
121910
131910
141910
151810
161810
171810
18189
19189
20189
21189
22179
23179
24179
25179
26179
27179
28179
29168
30168

How September really feels in Biel/Bienne

Once humidity and wind are folded in, September averages 0 days that feel above 32°C and 0 that feel at or below 0°C — the comfort signal a plain temperature reading hides.

Days feeling ≥ 32°C
0
heat index over the day's high
Days feeling ≤ C
0
wind chill below the day's low

September sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

Biel/Bienne weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 5th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / -2°8713.36.98.70.0
Feb / -2°78126.7100.2
Mar10° / 93144.811.61.9
Apr14° / 10515.32.313.33.4
May18° / 15117.80.214.84.6
Jun21° / 12°14617.5015.65.3
Jul23° / 14°15316.5015.35.9
Aug23° / 13°15715.90145.9
Sep18° / 10°11413.9012.45.3
Oct13° / 10913.60.510.63.5
Nov / 10113.33.59.11.0
Dec / -1°10614.56.68.40.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 25% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 15% of September, with mostly cloudy or overcast conditions the remaining 60%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
14753
24654
34654
44654
54555
64555
74456
84456
94456
104357
114258
124258
134159
144159
154159
163961
173961
183961
193763
203763
213763
223664
233664
243664
253664
263565
273565
283367
293268
303169

Chance of precipitation in September

Any precipitation

Biel/Bienne gets around 114 mm of rain over 13.9 wet days in September. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 47% and peaks near 48% on the wettest days.

0%20%40%60%151015202530
Rain chance (%)
148
248
348
448
548
648
748
848
947
1047
1147
1247
1347
1447
1547
1646
1746
1846
1946
2046
2146
2245
2345
2445
2546
2646
2747
2847
2948
3048

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

Most of September feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, September lands in the dry band about 77% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)
1603010
262299
364288
465287
567276
668275
769265
870264
971263
1072253
1173252
1273252
1375241
1475241
1576231
1677221
1778220
1879210
1980200
2082180
2183170
2284160
2385150
2486140
2587130
2688120
2789110
2890100
2990100
309190

Wind in September

Winds average 7 km/h in September.

Across September, daily wind ranges from about 7 km/h on the calmest days to 7 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (km/h)Feels
17calm
27calm
37calm
47calm
57calm
67calm
77calm
87calm
97calm
107calm
117calm
127calm
137calm
147calm
157calm
167calm
177calm
187calm
197calm
207calm
217calm
227calm
237calm
247calm
257calm
267calm
277calm
287calm
297calm
307calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 h 12 min at the start of September to 11 h 30 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 102 minutes over September. Sunrise moves from 5:55 AM to 6:35 AM, and sunset from 7:06 PM to 6:06 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.25:557:06
213.15:567:04
313.15:587:02
413.05:597:00
513.06:006:58
612.96:026:56
712.96:036:54
812.86:046:52
912.76:066:50
1012.76:076:48
1112.66:096:46
1212.66:106:44
1312.56:116:42
1412.46:136:40
1512.46:146:37
1612.36:156:35
1712.36:176:33
1812.26:186:31
1912.26:196:29
2012.16:216:27
2112.06:226:25
2212.06:246:23
2311.96:256:21
2411.96:266:18
2511.86:286:16
2611.86:296:14
2711.76:306:12
2811.66:326:10
2911.66:336:08
3011.56:356:06

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 3.57 kWh/m².

For context, solar energy here swings from a low near 1.02 kWh/m² to a high of 5.63 kWh/m² in July across the year — September's 3.57 kWh/m² falls in the middle.

012345151015202530
Solar energy (kWh/m²)Level
14.2Bright
24.2Bright
34.1Bright
44.1Bright
54.0Bright
64.0Bright
74.0Moderate
83.9Moderate
93.9Moderate
103.8Moderate
113.8Moderate
123.7Moderate
133.7Moderate
143.6Moderate
153.6Moderate
163.5Moderate
173.5Moderate
183.5Moderate
193.4Moderate
203.4Moderate
213.3Moderate
223.3Moderate
233.2Moderate
243.2Moderate
253.1Moderate
263.1Moderate
273.0Moderate
283.0Moderate
292.9Moderate
302.9Moderate
Planning a trip in September

Is September a good time to visit Biel/Bienne?

Our two travel scores rate September for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

5.3
Sightseeing
3rd-best month of the year
2.0
Beach & pool
4th-best month of the year

September is a reasonable time to visit Biel/Bienne for sightseeing.

What to pack for Biel/Bienne in September

From September's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In September, Biel/Bienne sees daytime highs around 18°C and nights near 10°C. Pack rain gear. About 14 days see rain.

rain gear

UV index in Biel/Bienne in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 5 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Biel/Bienne peaks around July 15 at about 8 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near January 1 at about 1 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 7 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighModerateLowJul 15UV 8Jan 1UV 1
UV index (midday)Level
Jan1Low
Feb2Low
Mar4Moderate
Apr5Moderate
May7High
Jun7Very high
Jul8Very high
Aug7High
Sep5Moderate
Oct3Moderate
Nov2Low
Dec1Low
Location & terrain

Where is Biel/Bienne?

Biel/Bienne sits at 47.1°N, 7.2°E, 434 m above sea level, in Switzerland. The nearest listed city is Grenchen, 13 km away.

SolothurnBernKönizNeuchâtelBurgdorfLa Chaux-de-FondsFribourg

Topography around Biel/Bienne

How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Biel/Bienne.

Within 3 km, the terrain around Biel/Bienne has significant variations in elevation — a maximum elevation change of 562 m around an average of 541 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 1,170 m; within 80 km, extreme variations in elevation — a maximum elevation change of 2,796 m.

The land around Biel/Bienne is covered by trees (50%) and artificial surfaces (24%) within 3 km, trees (44%) and grassland (26%) within 16 km, and trees (47%) and grassland (33%) within 80 km.

3 km
562 m
16 km
1,170 m
80 km
2,796 m
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Grenchen 13 km · Solothurn 23 km · Bern 26 km · Köniz 27 km · Neuchâtel 29 km · Burgdorf 30 km · La Chaux-de-Fonds 32 km · Fribourg 38 km

Switzerland travel facts

Travel advisory
Level 1
Exercise Normal Precautions
Power plugs
Type C / J
230 V · 50 Hz
Prices
≈ 112% of US
price level, 2025
GDP per capita
$114,769
2025
Happiness
7.0 / 10
World Happiness, 2025
Safe drinking water
97%
of population, 2024
Homicide rate
0.6
per 100k, 2023
Road deaths
2.2
per 100k/yr, 2019
Income group
High
World Bank
English
High
EF EPI 564
Religion
Roman Catholic 34%none 29%Protestant 23%other Christian 6%

Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.

Data sources

Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Biel/Bienne (47.1371°, 7.2461°, elevation 434 m), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).